An optical fiber sensor based on the Michelson inteferometer was constructed to detect AE(acoustic emission) signal occurred by matrix cracking in the laminated composites. To verify the validity of an optical fiber sensor as AE transducer, a forced vibration test for the composite beam was performed. In the experiment, the frequency of the detected signal was compared with such input frequency as that of AE by matrix crack. The experiment to investigate the survivability of optical fiber sensors was performed. In the experiment, it was advantageous to embed the optical fiber in the direction of reinforced fiber of the composite laminates to protect the optical fiber from matrix cracks of various types. Also, the effect of the embedded direction of the optical fiber on the sensitivity of acquiring AE signal was examined. Under the tensile loading, matrix cracking was detected by sensing AE signal for the cross-ply laminated composites, and it was confirmed by the replica method. As the density of matrix cracking was saturated, and the thickness of 90˚ layer became larger, the developed signal waves by the relatively large energy release were detected. In the frequency analysis of AE signal for matrix cracking, the upper limit of the characteristic frequency ranges was approximately to 120kHz.
